Phosphine containing cobalt carbonyl complexes are disclosed in U.S. Pat. No. 3,715,405, and are known to be useful as catalysts in the hydrogenation of cyclododecatriene to produce cyclododecene. These complexes are prepared by reacting octacarbonyl cobalt and tri-n-butyl phosphine in benzene.
Another process for the preparation of these complexes is disclosed in Lanzhow Institute of Chemical Physics, Academia Sinica, Lanzhow, China, No. 2:141-2 (1986). This paper disclosed preparing these complexes by the reaction of CaCO.sub.3, n-butyl phosphine, hydrogen and carbon monoxide at ca. 400 psi.